In the fields of computing and communications, users have become accustomed to ubiquitous access to their messages and messaging services. For instance, email can now be accessed on nearly any kind of communication device from almost any location. Likewise, unified communication technologies allow users to take and place phone calls and check voicemail through a variety of platforms, often integrated with their email.
Providing such high levels of availability and reliability at scale requires coordination across many systems and processes, which alone is a difficult task. Added to this are the challenges of keeping up with evolving technology and increased expectations. For example, users have come to expect access to messaging services not just from any device or location, but at any time and with the same rich features and responsiveness.
In response, some messaging services have evolved very complex architectures to provide these levels of availability and reliability. However, as services scale, such complexity can frustrate the development and deployment of new features and hinder maintenance and updates. For example, some email services call for very modular architectures that distribute messaging servers and content servers, and their associated roles, across diverse sets of server systems. While these modular arrangements have many advantages, they can lead to so much inter-server communication that a problem with just one component can negatively impact many others, thereby leading to sub-optimal user experiences.